Valve control system



M. BlRKlGT VALVE CONTROL SYSTEM Filed Dec. 3, 19:50

Sept. 19, l1933.

Patented Sept. 19, 1933 1,927,769 i Y VALVE coN'rRon SYSTEM Marc Birkgt, Bois-Colombes, France Application December 3, 1930, Serial No. 499,779, and in Belgium ySeptember 25, `1930 1 Claim.

The present invention relates to valve'control systems and, more particularly tothose designed for use in internal combustion motors for automobiles and like vehicles. y

One of the objects of the invention is to provide means for diminishing the noise and wear in the assemblies now interposed between the cam-shaft and valve for effecting the opening and closing movements of the latter.

Other objects will appear in the course of the detailed description now to be given with reference to the accompanying drawing, in which tlie single figure represents one illustrative embodiment of the invention.

15- supposing an internal combustion motor to be provided with valves driven by a cam shaft, there being interposed, between the cam and the valve stem, at least one intermediate element, for instance, a motor in which the valves a are driven by the rockers b, which are themselves driven by swivel rods c, pushed by push rods d directly by Athe cam e, and supposing the said motor has to be assembled so that the driving gear of its valves functions according to the invention, the '25* l following structures may be used:

A spring f acts, with a pressure inferior to that of the valve spring gear, in a direction corresponding to the opening of the said valve, rupon at least one of the elements disposed between the cam and the considered valve stem.

The spring f is, preferably, made to act on the push rod d and is, also preferably, given a strength to counterbalance the weight of the block constituted by the push and swivel rods.

If the push rod be constituted, as illustrated on the drawing, by a tubular element g carrying a roller h positioned to be pushed up by a cam e, the said tubular element sliding inside an appropriate guide z', the spring j may be advantageously '4Q disposed as follows:-

The guide z' is provided with an upper plane edge i. y

The upper portion g1 ofthe tubular element g 45, is given a diameter smaller than that of the sliding part in the guide i, the lower and upper portions being connected by a radial edge lc; the latter positioned so that, when the push rod reaches its theoretical low point, the radial edge lc is slightly in recess (for instance,l l mm.) with respect to the upper edge 7' of the guide i.

The upper portion g1 of the element g is rst provided with a washer Z which rests on the above mentioned edge y'.

The spring f is then mounted on l, its upper part being fixed to the upper portion of element g;

(Cl. 12S-90) in doing this, the tension of the spring vshould be adjusted to exert at rest the required pressure on the push rod. f

After the spring has been placed in position,

it is connected to the push rod, for instance, by t providing the cylindrical part y with a washer m. Washer m may then be xed in position by means of a split ring n fitting elasticallyinto a groove on the above mentioned cylindrical part. f

It is evident that, since the radial edge lc is, at rest, slightly in recess with respect to the upper edge y' of guide z', the spring exerts its pressure in the direction correspondingto the opening of the valve, this contributing to suppress rattling in the gear.

On the other hand, as soon as the push rod has been pushed up a certain amount, the `radial edge 7c strikes washer Z, which comes olf the upper edge j of guide i, the spring .being then lifted upl with the push rod.

Spring f, it will be seen,` functions to hold back the push rod at the end of its down-stroke.

Since the cam is designed, generally, so that any there is a clearance `between the push rod and' the inactive part of the cam for securing a good shutting of the valve, the braking action exerted on the push rod by spring `i contributes toprevent said push rod coming in Contact with the f cam on its inactive part. A furtherfunction of the spring consists in holding the push rod` in a f correct positionready for the next stroke.

The noise due to the push rod striking on the' y inactive part of the cam-as was usually the case heretofore, may thus be avoided. Y

ing the push rod in contact with the swivel rod,

-90 In addition to this, spring f contributes in keep the latter with the rocker and the rocker with the valve.

It should be borne in mind that the arrangement described above is quite different from certain former devices, whose driving gears are fitted with a spring for keeping the push rod against the cam. On account of the masses in motion, this spring (which acted in a direction Aopposite tively strong,l which resulted in rapid wear of the parts in functional contact.

It has been found that spring f appreciably reduces the noise of the driving gear, mainly vat high motor speeds.

Its presence being not an additional source of wear, the noise of the valve gear does not increase with time, and, the various elements being kept in contact, there is no danger of breakdown or running out of order.

-10O f to that of the applicant) had to be Vmade rela- Alined to the example described above.

The invention is, of course, by no means con- On the contrary, it may be applied so that the elastic system (spring f), instead of acting on the push rod, exerts its pressure on any other part of the 'l gear, for instance on the swivel rod, on the rocker, or on several parts simultaneously.

yWhat I claim isi--r l In anV internal combustion engine, a valve' provided with a valve stem, a cam, and means operated by'said cam for controlling said valve stem,

saidA means including an intermediate element",v and means operative on said intermediate ele-V ment as it approaches the end of'its movement nearest the low point of the cam to urge said Y ment is in a position between the two said shoulders, whereby the load is transferred to said fixed abutment whenthe element is at the end of its movement nearest the 10W point of the C am MARC BIRKIGT. 

